Trawl apparatus

ABSTRACT

A trawl apparatus equipped with an element for gathering and conveying it to a seafood/biomass receiving vessel. The trawl has an elongate, collecting cage which at an inlet is connected to the rear end of the trawl, and from the inlet extends into a second portion, defined by walls, roof and bottom which have openings for straining water, and is terminated in a downstream portion. A conveying hose—or pipe for conveying seafood/biomass from the cage up to the vessel opens into the downstream portion of the cage via a funnel. Air is supplied from the vessel for injection into the conveying hose—or pipe, to cause suction of the seafood/biomass from the cage to the vessel.

The present invention relates to a trawl apparatus equipped with a meansfor gathering seafood/biomass and conveying it to a seafood/biomassreceiving vessel, as defined in more detail in the preamble of attachedclaim 1.

During a trawling operation, a trawl is towed behind a trawl vesselusing adapted lines with or without otter boards, wherebyseafood/biomass such as fish, shrimp and krill and/or otherseafood/biomass is gathered in a trawl bag. After this trawl bag hasbeen more or less filled with seafood/biomass, it is normally hauled onboard the vessel and emptied. Alternatively, the trawl bag or sack maybe emptied whilst floating alongside the vessel. Some types ofseafood/biomass, such as for instance, krill, have a short liftetimeafter being gathered in the trawl and brought to the surface before theydie and rapidly begin to decompose, their value as a raw material thusdiminishing considerably. In general, it is important for all forms ofseafood/biomass that it should come to the vessel undamaged and asquickly as possible for further processing, as delays in this processusually substantially diminish the quality of the seafood/biomass.Seafood/biomass that is subjected to rough handling and crushing throughbeing gathered in a trawl bag and hauled on board the vessel, whereuponthe trawl bag is emptied, or by mechanical pumping from the trawl bagfor collection on board the vessel, will also be of reduced quality andvalue because of the damage it suffers. The reduction in value will alsoextend to by-products from seafood/biomass such as roe, liver or thelike. Seafood/biomass that is caught in a traditional manner will alsolargely be dead the moment it comes aboard the vessel.

In connection with trawl bags, it is known to equip such a bag with asorting grille or filtering grille to be able to separate out largerunits of seafood/biomass and marine animals, as for instance largerfish. The apertures in the sorting or filtering grille will determinewhat marine animals or seafood/biomass are filtered out of the trawlbag. There are also prior art solutions for separating small fish fromthe catch using similar systems.

It has also previously been suggested to use different forms ofmechanical pump solutions with an inlet opening in the end of the trawlbag so as to be able to pump the filtered content of the trawl bagdirectly up to a vessel on the surface, but the known solutions have notbeen particularly successful because of compression at the end of thetrawl bag and frequent blockages.

For further illustration of the prior art reference is made to theteachings of U.S. Pat. Nos. 1,447,553 and 3,440,752 and NorwegianPatents 109811, 35544, 166512 and 313261.

Accordingly, there is a substantial need to be able to enhance theefficiency with which undamaged and living seafood/biomass gathered bythe trawl is conveyed to a seafood/biomass receiving vessel. Theinvention is of particular importance for the gathering and conveyanceof krill, shrimp and other types of seafood/biomass, including all formsof fish, where conveyance to a production vessel for further processingand continuous, non-stop preservation on board can take place incontrolled forms during continuous or prolonged trawling

The apparatus mentioned in the introduction is characterised by thefeatures set forth in the characterising clause of attached claim 1.

The apparatus is characterised in that it can advantageously be usedduring uninterrupted, continuous or prolonged trawling, whereseafood/biomass is also in an uninterrupted or continuous manner over along period conveyed up to a receiving vessel.

Advantageous embodiments of the apparatus are disclosed in the dependentclaims.

The invention will now be described with reference to the attachedfigures.

FIG. 1 is a schematic illustration of a trawling operation which makesuse of a first embodiment of the apparatus according to the invention.

FIGS. 2 and 3 show on an enlarged scale details of the apparatus shownin FIG. 1, according to the invention.

FIG. 4 shows in even further detail the collecting cage that is anintegral part of the apparatus shown in FIGS. 1 and 3, according to theinvention. FIG. 5 is a schematic view of a trawling operation whichmakes use of a second, preferred embodiment of the apparatus, accordingto the invention.

FIGS. 6, 7 and 8 show on an enlarged scale details of the apparatusshown in FIG. 5, according to the invention.

FIG. 9 shows in even further detail the collecting cage that is anintegral part of the preferred apparatus shown in FIGS. 5 and 8,according to the invention.

FIG. 10 shows in more detail an example of a cleaning device formounting in the collecting cage.

In FIG. 1 the reference numeral 1 indicates a trawl which with the aidof towing lines 2 with or without otter boards or other devices forspreading the trawl opening (not shown) is towed behind a trawl vessel3. A conveying hose 4 extends from the trawl vessel 3 down towards thetrawl and at its end is connected to a collecting cage 5, where theinlet end 5′ of the cage 5 is connected to the rear end 1′ of the trawl1. In addition, from the vessel 3 there is provided a supply hose 6which extends downwards and either is connected to the conveying hose 4at a random point 4′ on the hose 4 between the trawl and the vessel,preferably connected as shown in FIG. 2. Alternatively, the connectioncan be made at a point 4″ close to the rear end 4′″ of the conveyinghose 4, as shown in FIG. 4, and the supply hose can then be run asindicated by the reference numeral 6′ in FIG. 1. It is intended to passa fluid, for example air or seawater, through the supply hose 6, which,by injector effect on introduction into the conveying hose 4 in thedirection of the vessel 3, will cause suction of seafood/biomass via thecollecting cage 5 and conveying hose 4 up to the vessel. Alternatively,the movement of fluid may be take place using the fluid displacementprinciple. In FIG. 1, the supply hose 6 is shown in part in a brokenline to illustrate the case where it is connected at the point 4″ asshown in FIG. 4. The supply hose 6 can also be uncoupled between thevessel 3 and the connection point 4″. The principle of handling andarrangement of the hoses and line can be varied.

As indicated in FIG. 2 on an enlarged scale, a weight 7 mayadvantageously be attached to the conveying hose to ensure that this isheld in position behind the vessel 3. This naturally applies also to thesupply hose 6. Adjustment of the position of the weight relative to theheight of the collecting cage can be done automatically using wirelesssensors and computer-controlled winches.

The collecting cage 5 which is preferably arranged at the open end 1′ ofthe trawl, is, as shown in FIG. 4, made in the form of an elongate bodywith an open front end 5′ and a rear end 5″ which passes into a funnel8. The collecting cage 5 is made having walls 9, 9′ and roof 9″ andbottom 9′″. These walls, roof and bottom may be made in the form of agrille or of a wire netting material or the like, the openings thusprovided being suitable for straining water. The walls and roof andbottom may be modularly constructed of sections, as indicated by thereference numeral 10, and joined in an appropriate maimer. The sections10 may advantageously have a circular or polygonal cross-section. InFIGS. 4 and 9 the collecting cage is shown, by way of example, having asquare cross-section. Mounted on the collecting cage may be a movable ormechanical cleaning device 21, indicated in FIG. 9 and shown in the formof an example in FIG. 10.

At the open front end of the collecting cage 5, indicated by thereference numeral 5′, there is, if desired/required, a cage sectionwithout a roof, as indicated by the reference numeral 11, so that thecollecting cage 5 in that section is open at the top so as to be able tocooperate with a screen or grille 12 that extends from the bottom edgeof the opening 5′ inwards and upwards in the collecting cage 5. Thepurpose of the grille is to ensure that seafood/biomass, for example,fish, or foreign objects over a certain size do not pass through thegrille, but are led up through the opening 11 and away from thecollecting cage 5. It may also be an environmental requirement that fishwhich are not to be caught by the trawl should be automatically sortedaway from the trawl. The grille can guide foreign objects through theopening in the roof of the cage as described above, or alternativelythrough the sides or bottom of the cage. In a simplified version, it isconceivable that the grille could be rotated 90° or 180° relative tothat shown in FIGS. 4 and 9 in order to make this possible. If thechannelling away of foreign objects is intended to take place, forexample, via two side walls, the grille could have a V-shape.

Suitable dimensioning of the apertures that will be found in the grille12 will allow the grille to be adapted to sort away all objects that arelarger than the desired seafood/biomass, for example, krill, shrimp,fish or the like. As shown in FIG. 4, the said funnel 8 passes into aduct portion 13 that is suitably bent so that the duct 13 opening 13′ ispreferably arranged parallel to the longitudinal direction of thecollecting cage 5. The duct 13 is connected to the conveying hose 4 atits end 4′″. The conveying hose 4 is, as indicated above, run up to thevessel 3, and the seafood/biomass that is conveyed to the vessel 3 canbe collected on board and further treated or further processed, andpreserved. On board the vessel, the conveying hose and the supply hosecould be coiled on hose drums with centre runout and swivels to enablethe hose length to be easily adjusted whilst the conveyance ofseafood/biomass up to the vessel continues. After or during theconveyance of the seafood/biomass to the vessel 3, it must be separatedfrom the seawater that accompanies it on its way up. This can beeffected, if necessary, by means of a deceleration device which reducesthe conveying rate and a suitable screening box for seawaterschematically indicated by the reference numeral 15. The fact that thetrawl in this way can be emptied continuously whilst it is towed throughthe water is essential for the quality that the caught seafood/biomasswill have, and will consequently also affect the quality of the finishedproduct.

As the seafood/biomass can be conveyed continuously, undamaged and aliveup to the vessel, it will also be possible to remove immediately anyunwanted seafood/biomass on board and subsequently return it to theocean in an undamaged and living form. The fisherman also has goodcontrol of what he catches and avoids catching large quantities ofunwanted seafood/biomass in the trawl bag.

Guide fins 14, 14′ which run in the longitudinal direction of thecollecting cage 5 are preferably, but not necessarily, arranged on theoutside of the collecting cage 5.

The amount of air or other fluid that is to be admitted into theconveying hose 4 by means of suitable devices on the vessel is optimisedto facilitate the most efficient continuous emptying of the collectingcage 5 in order to provide optimum conveying conditions for theseafood/biomass that is to be gathered and conveyed up to the vessel.

A slightly more preferred embodiment of the invention, and whichrepresents a modification of the embodiment that is shown and describedin connection with FIGS. 1-4, will now be described in more detail withreference to FIGS. 5-9, and the main focus will be on the structuralchanges compared with the embodiment shown in FIGS. 1-4. Elements inFIGS. 5-9 which have the same design or the same function as that shownin the embodiment in FIGS. 1-4 have been given the same referencenumerals, and will not be described in more detail below.

FIGS. 5-9 show a conveying hose 16 for conveying seafood/biomassgathered in the collecting cage 5 via the trawl 1 up to the trawlervessel 3. From FIGS. 5 and 8, it can be seen that the hose 16 in apreferred embodiment runs along the underside of the trawl 1. Then, asshown in FIGS. 8 and 9, the hose runs into the collecting cage 5 andpreferably along the bottom 9′″ thereof in the form of a conveying pipe16′ which at a rear section 5′″ of the collecting cage passes into aguiding funnel 17. The funnel opening will advantageously face the backwall 9″″ of the collecting cage. As shown in FIG. 7, a weight 7 will beprovided on the conveying hose 16 in order to hold it down, just as inthe embodiment in FIGS. 1 and 2, and the position of the weight mayadvantageously be in an area where the conveying hose 16 goes from aportion 16″ which is in the trawling direction to an upward extendingportion 16′″. The weight 7 is connected to the vessel 3 via a connectingline 18, corresponding to that shown in FIGS. 1 and 2.

Unlike the solution shown in FIGS., 1, 3 and 4 where a fluid, preferablyair, is supplied via the supply hose 6 either at a point 4″ on theconveying hose 4 or at a point 4′ on the conveying hose 4 at theposition of the weight 7, in the solution illustrated in FIG. 5 a supplyhose 19 supplies air or other fluid under pressure to an injector 20which is connected to the conveying hose 16 at a point which is at adepth that is substantially smaller than the depth at which the trawl 1and the collecting cage 5 are located. Thus, it is seen that theinjector 20 is located in a upper part of the upward extending portion16′″ of the hose 16. The injector 20 causes substantial suction to beproduced in the conveying hose, almost causing a siphon effect in orderto draw up seafood/biomass from the collecting cage 5 via the funnel 17,conveying pipe 16′ and the hose 16 to the vessel 3 via the injector 20.A considerable advantage of placing the injector 20 substantially closerto the vessel 1 than shown in FIG. 1, is that the conveying path for airor other fluid to the injector is shorter, which makes smaller demandsas regards the fluid pressure that will be required in the supply hose19 in order to bring the seafood/biomass up to the vessel, and thusreduces the power requirement needed for the supply of air or otherfluid to the injector. It is also a great advantage in connection with,e.g., inspection, maintenance or the like of the injector 20 that it isnot too far beneath the surface of the sea. Adjustment of the level atwhich the injector is positioned relative to the collecting cage can bedone automatically using wireless sensors and computer-controlledwinches.

FIG. 10 is a purely schematic illustration of the principle of apossible cage cleaning device 21 consisting of a rotating bladed wheel22 where the blades 22′, when they rotate about an axis of rotation 23and are under a semi-circular cover 24, will be horizontal or almostparallel to the adjacent wall, bottom or roof of the collecting cage toreduce water resistance, whilst when the blades 22′ move outside thefront edge 24′ of the cover, they will turn to stand almostperpendicular to the adjacent wall, bottom or roof of the cage.

As mentioned in the introduction, the gathering and conveyance of, forinstance, krill and other biomass will be critical as regards time, as,the quality of, for example, krill that is to be further treated andprocessed may easily deteriorate because it dies too long before theprocessing takes place. Swift conveyance of living individuals up to thevessel and thence directly to a continuous processing process has theeffect of ensuring that the protein content and the quality of thegathered seafood/biomass is optimal and considerably better than whatcan be achieved with the known solutions. As also mentioned in theintroduction, the quality of the seafood/biomass such as krill or fishthat is first subjected to crushing during the gathering in the trawlbag and is then subjected to further crushing and damage when the trawlis hauled on board the vessel and emptied, or if the trawl is emptied bymechanical pumping, will also be enhanced by using the apparatusdescribed, as the seafood/biomass is subjected to far less roughhandling/damage during collection and conveyance to the vessel, andmoreover it reaches the vessel whilst still alive.

Although the present invention will be especially suitable for thecollection and conveyance of, for example, krill, it will be obviousthat the apparatus can also be used for any form of seafood/biomass thathas larger or smaller individual dimensions or form. Thus, it should beclear that the invention is not limited to use at sea, but can just asreadily be used in fresh water or inland waters or lakes.

The design of the collecting cage 5 shown in the figures is of coursenot a limitation as regards how the collecting cage may be designed andequipped, or of what suitable materials it is made. There may, forexample, be provided devices known per se in the form of sensors, which,for instance, may be wireless, for monitoring the position of thecollecting cage in the water, depth, flow etc.

Although the use of filtering grille 12 has been illustrated anddescribed, it may in some circumstances be neither necessary nordesirable.

1-11. (canceled)
 12. A trawl apparatus with a trawl (1) and a means forgathering seafood/biomass and conveying it to a seafood/biomassreceiving vessel (3), wherein the trawl (1) has an elongate, rigid orflexible collecting cage (5) which at an inlet opening (5′) is connectedto the rear end region (1′) of the trawl, and from the inlet openingextends into a second portion, which has openings for straining water,and is terminated in a downstream portion (5″; 5′″); wherein a conveyinghose or pipe (4; 16, 16′) for conveying seafood/biomass from thecollecting cage (5) to the vessel (3) opens into the downstream or aftportion (5″; 5′″) of the cage (5) via a funnel (13; 17); wherein air orother fluid is supplied from the vessel (3) via a supply hose (6; 19)for injection into the conveying hose—or the pipe (4; 16), in order, byinjector effect or fluid displacement technique, to bring theseafood/biomass from the collecting cage (5) up to the vessel (3), andwherein a filtering grille (12) is provided to filter away seafood orbiomass which is not to be led to said funnel, characterised in that thesupply of air or other fluid is, via the air supply hose (6; 19),adapted to be injected at a point on the conveying hose or pipe (4; 16)by means of an injector (20) in an upper area of the conveying hose orpipe (4;16) which has a marked upward gradient towards the surface ofthe sea.
 13. An apparatus as according to claim 12, characterised inthat the injector (20) is depth adjustable to be positioned at arequired location in said upper area.
 14. An apparatus as disclosed inclaim 12, characterised in that said sorting or filtering grille (12) isprovided at the inlet opening (5′) of the collecting cage (5) and isarranged to extend obliquely inwards and upwards, downwards and/orsideways in the collecting cage (5); and that a portion (11) of roof,bottom and/or walls of the collecting cage (5) located at a downstreamend of the grille (12) is open, so that seafood/biomass, for example,fish, or foreign objects over a certain size do not pass through thegrille (12) but are led through the at least one open portion (11) andaway from the collecting cage (5).
 15. An apparatus as disclosed inclaim 12, characterised in that the openings for straining water areformed of a self-cleaning grating or grille structure which may be rigidor flexible.
 16. An apparatus as disclosed in claim 15, characterised inthat at least one wall, roof or bottom portion of the collecting cage isequipped with a mechanical device for effecting the cleaning of thegrating or grille structure.
 17. An apparatus as disclosed in claim 12,characterised in that the collecting cage (5) is modularly constructedof joined sections (10).
 18. An apparatus as disclosed in claim 12,characterised in that the funnel is inside the cage (5), the mouth ofthe funnel (17) facing and spaced from closed aft wall (9″″) of the cage(5).
 19. An apparatus as disclosed in claim 12, characterised in that inconnection with, after or during the conveyance of the seafood/biomassfrom the collecting cage (5) to the vessel (3), there is provided astraining device (15′) to separate seafood/biomass from seawater whichaccompanies it during its conveyance from the collecting cage (5) to thevessel (3), and that in connection with the straining device there isprovided a deceleration device (15) which is designed to reduce theconveying rate of conveyed seafood/biomass.
 20. An apparatus accordingto claim 12, characterised in that sensors (21) are provided on or inconnection with the collecting cage (5) for monitoring theposition/orientation of the collecting cage (5) in the water, depth,water flow etc.
 21. An apparatus as disclosed in claim 13, characterisedin that the openings for straining water are formed of a self-cleaninggrating or grille structure which may be rigid or flexible.
 22. Anapparatus as disclosed in claim 14, characterised in that the openingsfor straining water are formed of a self-cleaning grating or grillestructure which may be rigid or flexible.
 23. A trawl apparatusincluding a seafood/biomass gathering member, a trawl, and aseafood/biomass conveyor, said seafood/biomass conveyor being connectedto transport seafood/biomass from said trawl to a vessel, said conveyorincluding a hose, said hose having an upper region, said upper regionhaving an upward gradient, towards the surface of the sea, wherein saidapparatus includes an injector mounted in said upper region of saidconveyor having said upward gradient, said injector being operable tourge seafood/biomass through said hose from the trawl to the vessel viasaid upward gradient.
 24. A trawl apparatus according to claim 23,wherein: the trawl has an elongate, rigid or flexible collecting cage;said collecting cage being chosen from the set of collecting cagesconsisting of (a) rigid collecting cages and (b) flexible collectingcages; said elongate collecting cage has a first portion, said firstportion including an inlet opening; said inlet opening is locatedrearwardly of said trawl, and is connected thereto; said collecting cagehas a second portion, said inlet opening leading into said secondportion; said second portion having openings therein, said opening beingoperable to strain water; said collecting cage has a third portionmounted downstream of said second portion a funnel is connected to saiddownstream portion; a filtering grille is mounted upstream of saidfunnel to filter away seafood or biomass which is not to be led to thefunnel, a conveying hose is connected to said funnel, said conveyinghose being mounted to convey seafood/biomass to the receiving vessel;and a fluid supply hose is mounted to inject fluid supplied from thevessel into the conveying hose via the injector to urge seafood/biomassto pass from said collecting cage to the vessel.
 25. An apparatusaccording to claim 23, wherein the injector provides for injector effector fluid displacement technique, to bring the seafood/biomass from thecollecting cage up to the vessel.
 26. An apparatus according to claim23, wherein the injector is depth adjustable to be positioned at arequired location in said upper area.
 27. An apparatus according toclaim 24, wherein said sorting or filtering grille is provided at theinlet opening of the collecting cage and is arranged to extend obliquelyinwards and upwards, downwards and/or sideways in the collecting cage;and a portion of roof, bottom and/or walls of the collecting cagelocated at a downstream end of the grille is open, so thatseafood/biomass, for example, fish, or foreign objects over a certainsize do not pass through the grille, but are led through at least oneportion and away from the collecting cage.
 28. An apparatus according toclaim 24, wherein the openings for straining water are formed of aself-cleaning grating or grille structure.
 29. An apparatus according toclaim 24, wherein at least one wall, roof or bottom portion of thecollecting cage is equipped with a mechanical device for effecting thecleaning of the grating or grille structure.
 30. An apparatus accordingto claim 24, wherein the collecting cage is modularly constructed ofjoined sections.
 31. An apparatus according to claim 24, wherein thefunnel is inside the cage, and the mouth of the funnel faces and isspaced from the closed aft wall of the cage.